The first ODI between South Africa and England in Cape Town has been called off, less than an hour before the toss.
ESPNcricinfo understands that the postponement relates to positive Covid-19 tests within the South Africa camp, amid suggestions that protocols were breached during the T20I series.
All players and support staff are set to undergo another round of tests on Friday afternoon, in the hope of starting the series on Sunday.
A CSA statement said: "This decision results from a player from the Proteas team testing positive for Covid-19 after the teams' last round of scheduled testing performed on Thursday ahead of the ODIs.
"In the interests of the safety and well-being of both teams, match officials and all involved in the match, the acting CEO of CSA, Kugandrie Govender as well as the CEO of the ECB, Tom Harrison, have agreed to postpone the first fixture to Sunday."